Party-line telephone system.



10.768,272. v 12ATBNTEDAUG.23,1904.

T. c. BRAKE. PARTY LINE TELEPHONE SYSTEM..

APPLICATION FILED NOV. 9, 1903.

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No. 768.2272.4 f PATENTED Amma, 1904.

T. c. BRAKE. v

PARTY 'LINE TELEPHONE SYSTEM.

l APPLICATION FILED NOV. 9, 1903. Y N0 IODBL. l 2 SHEETS-SHEET 2,

Patented August 23, 19u4.

PATENT OFFICE, f

THOMAS O. DRA-KE, OF MALTA, OHIO.

PARTY-LINE TELEPHONE SYSTEM,

SPECIFICATION forming part of Letters Patent No. 768,272, dated August 23, 194.

Application led November 9, l903. Serial No. lilOfltV.v (No model.)

To a/ZZ lwhom t may concern:

Be it known that I, THOMAS O. DRAKE, a citizen of the United States, residing at Malta,

in the county of Morgan and State of Ohio, have invented certain new and useful lImprovements in Party-Line Telephone Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.-

My invention relates to party-line telephone systems with selective or non interfering bells. i

' The object of my invention is `to provide an improved method'of selectively ringing biased polarized call-bells in party-line telephone systems.

In the prioi' art it has been proposedy to connect two oppositely-biased polarized bells on either side of a'metallic circuit and ring over the dierent circuits formed by using the ground as a return-circuit for both sides of the line. rIhe bells or ringers have been biased by means of a light spring acting upon the pivoted armature to retain the armature normally in a position toward which it would tothe current sent out in a predetermined difA rection, the other ringer being' unresponsive,

for the reason that the current operating oneA will assist the light spring in retainingthe bias of the other. In systems of this character the biasing-spring of theA ringer has been depended upon entirely forthe return or 're-4 tracting stroke of the polarized armature after having been actuated against the bias by a pulsation of the proper polarity, and carefull and exact adjustment of the armature and spring with reference to the energizing pnlsating current has been` required in orderto obtain satisfactory operation ofthe ringer.

If the pulsations vary in strength by reasonof a change in speed of the generator or from change in resistance of the line, the bells requirean adjustment to conform to the varying condition in order to operate perfectly.

One object'of my invention is to obviate this deiiciency and make it possible to operatea biased bell under greatly varying conditions as regards speed or frequency of the Iringing-machine and the resistance of the line-circuit.- y

My invention contemplates giving the polarized armatures of the ringers a certain amount of bias either by gravity or by a spring, magnet, or other means; but-I do not depend upon the bias entirely for the return or retracting stroke or movement of the armature after having been actuated in opposition .or against the biasing forceby a pulsation or alternation of the required strengthand'polarity. My invention contemplatesemployvving an alternation or half-wave of4 adeiinite strength and polarity to assist the biasing force in actuating the polarized armature in the direction of its normal bias o'r trend. In practice I prefer to arrange suitable ringing apparatus in such a manner as to obtain an alternation or half-wave for assisting the bells `biasing force inthe retracting stroke of the armature of approximatelyv one-third the electromotive force of the alternation or halfwave employed to actuate thearmaturein opposition to the biasing force. Throughout the specification and claims I will referto the alternations or half-waves `which are intended to actuate the polarized armature against thefbiasing force as the heavy or major alternations or halfwaves and to the alternations or half-waves vwhichl are intended to assist'the biasing force in the retracting stroke of the armature as L minor alternations or halfwaves. l L

By means of my present invention I amenabled to operate polarized bells entirely satisfactory by mounting the same in such a and ballonly are depended upon for the biasing force of `the armature, and as the usual spring is obviated the ringer is much more sensitiveand will therefore operate'v'through greater. resistance.

In practice I prefer to mount the'bell sov lmanner that the weight of the tapper-wire f IOO that the same isbiased by the weight of its own moving element; but I do not limit my invention to bells mounted in this manner, as

any polarized bell properly biased with a 1 l l l l l and static capacity of such lines discharge current throug'h the biased bells in the wrong direction at the instant of interrupting' the generator-circuit to prod uee the pulsating` current. By operating the biased bells in the manner herein set forth the circuit through the ringing' apparatus is not interrupted, as is the case with a pulsating-current generator. Therefore the discharge due to static capacity and inductance finds path through low resistance at the ringing apparatus instead of throughthe biased bells at the subscribers stations.

An important feature of my invention relates to the amount of resistance practical to place in each bell-circuit. According' to my invention the ringers or the circuits including the ringers may be as high as fifty thousand ohms; but in practice the resistance is preferably less, for the reason that fifteen thousand to twenty thousand ohms has been found sufficient for all conditions under which the system may be required to operate at the present time. This is accomplished when obviating the usual type of biased ringer in which pulsating current is counteracted by a spring. This comparatively high resistance gives to my system several important features which are not present in party-line systems in use before my inventionnamely, the constant loss of current throug'h the ring'ers when working the system on common battery-circuits is reduced to a minimum, the margin in line resistance between the talking' and signaling condition of the system is suiiicient for properly operating the line-relays and cord-circuit relays in common battery systems, and the kick7 due to self-induction and static capacity of the switchboard apparatus will not interfere with the biased bells not being' signaled.

In so far as connecting the ringers with the line-circuit is concerned my invention does not contemplate a method different from systems in common use at the present time; but instead of employing the usual plus and minus pulsating current to selectively operate the bells I employ an alternating' current, as before stated.

In practice I employ an alternating cur rent with approximately ninety volts potential in one alternation or half-wave and approximately thirty volts potential in the alternation or half-wave of opposite sign. l

rent by connecting a source of steady current, such as a battery in multiple or a derived circuit, with an alternating generator oi' the usual type for ringing' telepho1n\bells. The source of steady current is employed to suitably counteract the positive alternation or half-wavefrom the altermiting` generator for ringing' a bell biased in one direction and to suitably counteract the negative alternation or half-wave from the alternating generator for ringing' a bell biased in the opposite direction.

Referring to the accompanying drawings, Figure l is a diagrammatic view of a fonr party telephone system operated aceordine' to myinvention. Fig'. Qisan embodimentot my invention in which a single source of steady current is adapted to counteract the positive or negative alternations from an alternating generator. Fig'. 3 is an extraction of Fig. 1. Fig'. 4 is an embodiment of my invention in which two alternating' generators are eniployed, each generator being connected in multiple with an individual source of steady current; and Fig'. 5 is the preferred type of polarized bell biased by the weight of its moving element.

Like characters refer to like parts in Fig. l.

Referring to Fig. l, the limbs l a of the party telephone-line extend to the four substations, and the transmitters /1 and receivers c are connected between the metallic limbs` a al, the receivers being adapted when on the switch-hooks to open the circuits, and thus cut the telephone apparatus out of circuit in the usual manner in the idle condition of the system. At substations A and B are provided biased polarized bells d and d', respectively, the bells being biased in opposition lo each other and connected in multiple with limb r'l/ and the ground as a return-circuit. One of the bells, d, is biased, so that a positive major alternation or half-wave will actuate the polarized armature in opposition tothe biasing force and a negative minor alternation or half-wave will assist the biasing force in the return stroke of the armature, and the other bell is biased oppositely, so that anegative major alternation or half-\vave will actuate the polarized armature in opposition or against the biasing force and a positive mino1' alternation or half-wave will assist or augment the biasing force in the return stroke of the armature. At su bstations C and Dare provided biased bells e fr', respectively,the bells being connected between limb u and the ground in the same manner as the bells on the other side of the metallic circuit. Bell f is biased, so that a positive major alternation or half-wave will actuate the polarized armature against the biasing' force, and a negative minor alternation or half-wave will assist the biasing force in the return stroke of the armature, while the other bell, (f, is olripositely biased and prefer to produce the desired alternating curlr requires a negative major alternation or half- JOO wave to counteract' the bias and a positive minor alternation or half-wave to assist thev biasingforce -in operating the bellto signal.

Thelimbs a a of thetelephone-line terminate j in a spring-jack f at the central station, which v according to thisl diagram 'comprises' linecontact-anvils being connected directly with 1 relay fg.

a common battery f5. and an individual-line When any one of the receivers are removed from the switch-hooks, the common battery energizes the individual-line signal to apprise the central operator that her assistance is required. When the receivers are re'- stored to the switches, the line-signalis inactive, for the reason that the high resistance of the ringersbridged with both sides of the line to ground allow but a very slight current toes cape through the line-signal. The operators listening-in key has been omitted from the drawings for clearness; but it may be oi' any suitable arrangement as employed in the art.rv The operators cord is provided with four selective ringing-keys oi' the usual construction.

4which-'for ready .identilication vare numbered l, 2, 3,' and 4. The keys are provided with contact-springs L/c Z/ m', and z/ if," Z m, respectively. normally resting against contacts which are adapted to maintain the cord-circuit continuous to amate plug, which plug is not shown. All ofthe contact-springs have suitable back contacts by means of which the various combinations of positive and negative steady current and alternating `ringing-current may be connected with the proper limb of the metallic circuit for selectively ringing the desired bell.

Referring to Figr, the arrangement and construction of a suitable ringer orcall-bell may b e understood. This is the apparatus by4 means of which an audible signal is produced at the various substations. The general construction of the ringer is similar to the com# mercial forms n'ow universally adopted intelephone-work and depends for its mode of action upon the sameprinciples.

In front of the electromagnets, the coils w w,of which are connected in series,V is pivoted in a yoke w2 an armature w3. lThis arusual manner.

for striking the gongs.

vto line and positive to ground.

with magnet w above magnet @1f-so that the 'tapper-wire wr and ball will vibrate ina vertical plane and be held against gong .w by the force of gravity, thus biasing the bell by the Weight of its own moving element. I am vaware that this is not vgood practice if the ringers were to be actuated by means of plus and minus pulsating current according to the prior art; but with my system 1t 1s perfectly practicable and desirable to mount the ringer movement in this manner.

Referring to Fig. 2, n2 is a generator' of alternating current of suitable frequency and,

steady current n and adapted to bridge' `the v source of steady current with the line of in the .act of selectively ringing either one of thev biased call-bells.l The source of steady current is connected in series withl an impedance or resistance coil 01, in `order to preventshortl circuit of the alternating generator n2 through the battery or steady-current source. In the act ofselectivelyv ringing call-bell ezto the eX-v clusion of call-bell e3 the pole-changing key o connects the positive terminal of the steady source n with the line-circuitand the negative terminal to ground. The circuitmay be traced through spring 05, back contact 0', impedance or resistance coil @'battery n, contact-anvil 04, vspring 0 to ground. When the l source vof steady current is'thus connected in,

multiple with the alternating generator n2 for ringing call-bell e2, the negative alternations orhalfwaves are partially counteracted, thus producing the major ,positive alternations or halt' waves requiredy to actuate call-bell @2 against the biasing force and the minor nega-l tive alternatioris or half-waves required to assist the biasing force in the return stroke or' the biased armature. In the act of selectively ringing call-bell v@3 to the exclusion of callbell e2 the polechanging key 0 is depressed. thus reversing the polarity of the steadycur rent source and' connecting'the same negative In the de` pressed condition of the key the circuit may be traced through spring 05, contact-anvil 03;

Vnegative pole of battery n, impedance-coil or IOO resistance-coil nf, contact-anvil 02, spring 06 to ground. When the source of steady current is thus connected in multiple with the alternating generator n2, the positive alternations or half-waves are partially counteracted by the steady current, thus producing the major negative alter-nations or liali`-waves required to actuate call-bell e3 against the biasing force and the minor positive alternations or halt`- waves required to assist the biasing force in the return or vretracting strokes of the biased armature. It is obvious that either callbell may be selectively rung and the oppositelybiased call-bell silenced by simply reversing the polarity of the steady current connected in multiple with the usual bell-ringing or alternating-current generator. l do not' limit myself to a single source of alternating current and a single source of steady current, is diagrammed in Fig. 2, as two alternating generators and two sources of opposite-polarity steady current may be employed, each alterating generator being connected with a particular polarity of steady current for operating one particular biased bell, as is diagrammed in Fig. t, where r is a positive steady-current source connected with an alternating generator fr and adapted topartially i counteract the negative alter-nations or halt'- waves from generator fr in the act or' selectively ringing call-bell el on pressing key y), which key connects battery fr through the impedance-coil r2 in multiple with the generator fr. In this same figure, Q is a source or' negative steady current adapted to be connected in multiple with generator q for partially counteracting the positive alter-nations or half-waves for producing the major negative alternations and the minor positive alternations required to selectively ring call-bell c5 on pressing key 29.

Referring to Fig. 3, my invention is represented as operating with two sources ot' steady current and one source of alternating current.

In this figure c represents a generator of belli ringing current. This generator may be an alternator or a pulsating-current generator. ln case of it being a pulsating generator a condenser s is inserted into the circuit, the function of which is to change the pulsating current into alternating current, according to wellknown principles. In practice the condenser is usually connected in the circuit, as shown, in order to prevent a metallic connection between the two sources of current, whether the i are bridged with the line-wire c, which ter- The i the steady current t partially counter-acts thr` alternations or half-waves which areol opposite polarity to the stezulv-current polarity, thereby producing the major and minor alternations or half-waves required to operate callbell e". lVhen it is desired to ring the negativelybiased call-bell el and have the positively-biasral bell remain silent, key p is pressed. This operation connects the negative steady current fj, through i1u])edance-coil u', and also ringi11g-generator w, throughcondenser s, with line-wire es, and through bells e and f7 in multiple toground, as belore. (lailbell el is biased to ring when the steady current f' partially counteracts the alternations or half-waves which are of opposite polarity to the steady-current polarity, thereby producing the major negative alternations and the minor positive alternations necessary to ring call-bell c7. lt is obvious that when ringing call-bell e the counteracted alternations or half-waves are ot' opposite polarity from those which were counteracted when ringing callbell c7.

Referring to Fig. l. the circuits will be traced for operating 'tour substations on a metallic circuit. The alternating` generator u' has one terminal grounded and the other terminal connected with back contacts /fi /i m72 ot' the select-ive ringing-keys 1 :l 23 l, respectively. Keys 1 and 8 have their back contacts /lf and respectively connected through impedance-coil i with the source oi positive steady current f, the negative terminal of which is grounded. keys 2 and -1Y have their back contacts and m respectively connected through impedance-coil j with the source of negative steady ciu-rent j, the positive terminal ot which is grounded. The coils j' luay be ordinary resistance or retardation coils, and their function is to prevent short circuit of the alternating generator through thc sources ol steady current when operating the various selective keys to ring the substation-bells. Then it is desired to ring the bell at substation A, the key 1 is pressed, This will close thecircuit from alternating generator .r and positive. steady current in multiple through back contacts /fi 7a3, key-spring cord-straml c', tip r/ oi' plug g, short-line springj", limb a ol the metallic circuit, and through the two bells d and (W in multiple to ground. T he steady-cu rrent sou ree being connected positive to lineand in multiple with the alternating generator a', will partially counteract the negative :lternations or half-waves of generator fr, thereby producing the required major and minor alternations ior selectively operating the biased call-bell f/ at substation A, the major alternations actuating the biased armature in opposition to the biasing force and the lninor alternations ass' `ting the biasing force in the return or retracting strokes of the armature. dien it is desired to ring the bell at substation B, the

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multiple with the alternator m, will partiallyV counteract the positive alternations or halfwaves of generator fr, thereby producing the required major and minor alternations for selectively operating the biased call-bell cl at substation B, the major negative alternations actuating the biased armature in opposition to the biasing force exerted thereon and the minor positive alternations assisting' the biasing force inthe return or retracting strokes of the armature. the bell at substation C, the key 3 is pressed. This will close the circuit from alternator fr and positive steady current z' in multiple through back contacts Z2 Z3, key spring l, cord-strand c2, sleeve g2 of plug g, long-line spring f2, limb cd of the metallic circuit, and through the two bells c e in multiple to ground. The steady-current source c', being connected positive to line and in multiple with alternator m, will partially counteract the negative alternations or half-waves of generator m, thereby producing the'required major and minor alternations for selectively operating the biased call-bell e at substation C, the major positive alternations actuating the biased armature in opposition to the biasing force exerted thereon and the minor negative alternations assisting the biasing force 1n the return or retracting strokes of the armature. When 1t is desired to ring the bell at substation D, the key L is pressed..

This will close the circuit from alternator .fc and 'negative steady current j in multiple, throughback contacts m2 mi, key-spring m, cord-strand c2, sleeve g2 of plug g, long-line spring f2, limb a of the metallic circuit, and through the two bells c e in multiple to ground. The steady-current source j, being connected negative to line and 'in multiple with alternator m, will partially counteract the positive alternations or halfwaves of generator thereby producing the required major and v'rninor alternations -i'or selectively operating the biased bell e at substation D, the major negative alternations actuating the biased armature in opposition to the biasing force exerted thereon and the minor positive alternations assisting the biasing force in the return or retracting strokes of the armature.

l In circuits of this character some means are gree that the bells will remain silent.

Vhen it is desired to ringV of almost any character.

'for instance, on depressing key l to ring sub.'-

station A key-spring /t grounds limb a while ringing' over limb a. The circuit may be traced from ground through back contact tf, key-spring 7L', cord-strandc2, sleeve'gZ- of plug g, long-line spring f2, and limb a. Should a telephone receiver be removed from a switch-hook at any of the substations while ringing-current is beingprojected over the line, the low resistance thus provided through the telephone instrument and line to ground will shunt the ringing-current to such a (Slee.- lective keys 2, 3, and 4 are likewise provided with grounded back contact 704, Z", and mi', respectively, the function of which is to ground one limb ofthe line while ringing over the'other.

In Fig. I I .have shown a connection-plug equipped with four party-line keys. Instead of providing this number of keys for each cord-circuit of the switchboard a single set ofkeys may be providedY and adapted to be connected with any particular set ot' cord conductors that may be for the time in use.

Throughout this specification I have shown and described my system with ground-returns and for metallic circuits; but this is by no means the limitation of my invention, it being readily applicable to ycommon return systems and telephone-switchboard circuits I have also shown and described my vinvention in connection with a specific line-circuit in which the bells are permanently grounded or connected therewith; but it is obvious that my invention is applicable to operating biased-bell party-line systems in which the bells are normally dis,- connected from the line, but in operative relation therewith, and adapted to be connected with the line in their operative condition by suitable means, such as relays; f A A By the term engaged steady current or "means to engage the steady current, as employed'in certain claims, I wish to be understood as meaning the steady current which is in use or connected with the line-circuit when selectively ringing one of the biased call-bells.

Having described my invention, what I claim as new, and desire to secure by Letters y Patent, is,- l Y A l. In a party-line telephone system,the com,- bination with a line-circuit, oftwo oppositelybiased call-bells connected -therewith i-n their operative condition, means to selectively operate one of the bells tothe exclusion of the other, the means comprising an alternatingcurrent generator connectedwith the line, and a source of steady current connected in a derived circuit with said alternating generator orpartiall y counteracting one of the alternations or half-waves generated by said stantially as described.

2. In a party-line telephone system, the combination with a line-circuit, of two oppositely- IOO generator, subbiased call-bells connected therewith in their operative condition, one et' said bells being organized to respond to a major positive alter'- nation and a minor neg'ative alternation, and the other bell being organized to respond to a major negative alternation and a minor positive alternation, means connected with the line-circuit to selectively operate one ot' said bells to the exclusion ot' the other, the means consisting of an alternating generator, a source of steady current connected in multiple with the generator Jfor partially counteracting one of the alternations, and an impedance in series with the steady-currentsource to prevent short-circuit ot' the altern ating generator, substantially as described.

3. In aparty-line telephone system,the combination with a line-circuit, otl two oppositelybiased call-bells connected therewith in their operative condition, one ot' said bells being organized to respond to a major positive alternation and a minor negative alternation, and the other bell being organized to respond toa mai jor negative alternation and a minor positive alternation,and means organized to selectively ring either one et' the bells to the exclusion otl the other, the means consisting of an alternating generator, and a source ot' steady current connected in multiple with said generator tor suitably counteracting one alternation or halt'- wave in the act o'tl selectively ringing one bell,

the other bell being organized to respond to a major negative alternation and a minor posit tive alternation, and means organized to selectively ringl either one ot' the bells to the exclusion eti4 the other, the means consisting ot' an alternating generator, and a source ot' positive steady current connected in multiple therewith for producing the major positive alter-nations and minor negative alternations, and a source of. negative steady current in multiple with said generator for producing the major negative alternations and minor positive alternations, and means in series with the steady-eurrent sources to prevent sliort-circuit ot' the alternating generator while ringing the callbells, substantially as described.

5. The combination in aparty-line telephone system, of biased call-bells connected with a line-circuit, an alternating-current generator connected with the line-circuit to selectively operate the call-bells biased in one direction and a source ot' steady current connected in multiple with the alternating generator for l suitably counteracting the altcrnations or halt-waves olone polarity, whereby the armatures ot the biased bells intended to ring` will be actuated against the biasing Ytorce by major alternations or half-waves, and actuated toward or in the same direction as the biasing force by minor alternations or hal t-wa ves, sul stantially as described.

(i. Vln aparty-line telephone system, two polarized call-bells biased in opposition to each other and connected with a line-circuit tor signaling, the bells being organized to operate with a heavy alternation ot' current to actuale the biased armatures oi the bells in opposition to the biasing torce exerted thereon, and a light alternation of current ot opposite polarity to assist the biasing force in the mieration ot' the biased armatures in the direction ot their normally biased trend, and mea ns organized to be connected with the line-circuit by means ot' suitable keys for producing the required heavy and light alternations et current the means consisting ot' an altern ating-current generator, and a source ot steady current connected in multiple with the alternating-generator, substantially as described.

7. ln a party-line telephone system, two polarized call-bells biased in opposition to each other and connected with a line-circuit for rate with a heavy alternation ot current to aetuate the biased armatures ot' the bells in opposition to the biasing torce exerted thereon, and a light alternation of current ol opposite l polarity to assist the biasing force in the operation et' the biased arn'iatures in the direction ot' their normally biased trend, an alternating current generator and a source oi steady current connected in multiple with the generator for producing the heavy and light alternations required to operate one ot the g biased bells, and means to reverse the polarl ity of the steiuly-eurrent source tor producing i the heavy and light alterimtions required to l operate the oppositely-biased bell,and an iml pedance in series with the steady-current source to prevent short-circuit ot tl alternating-current generator, substantially as described.

i 8. In a party-line telephone system, two pol larized call-bells biased in opposition to each l other and connected with a line-circuit tor signaling, the bells being organized to operate with a heavy alternation ot current to aci tuate the biased armatures oi the bells in opposition to the biasing force exerted thereon, and a light alternation ot current ol5 opposite polarity to assist the biasing vtorce in the op- I eration et' the biased armatures in the direction of their `normally biased trend, an altery nating-current generator, a source ol positive l steady current, and a source ot negative l steady current, means organized to connect the alternating-current generator and positive steady current in multiple with the linelOO IIO

circuit for selectively ringing'one of the bells Ato the exclusion-ot` the other, and means ori ltor through the steady-current sources while ringing, substantially as described. Y

, A 9. In aparty-line telephone system, the combination with a line-circuit, oi' two polarized call-bells connected therewith for selective sigtially as described. l

naling, said bells being biased in opposition to each other, one oi' said bells being organized to operate with a heavy positive alternation of vcurrent whichwill actuateits armature in opposition to the biasing trend, anda light negative `alternation of current which will yassist the biasing trend in the operation of its armature in the directionof its normal position, the other bell being organized tooperate with a heavy negative alternation of current which will actuate its armature in opposition to the biasing trend, and a light positive alternation of current which will assist the biasing trend in theoperation of its armature in the direction of its normal position, means for producing the required heavy and light alternations oi' current for selectively operating the bells, the means consisting of an alternating-current generator and sources of positivesteady current and negative steady current, and apparatus to connect either positive or negative current in multiple with the alternating generator when operating either bell to the exclusion of the other, substan- 10. In a party-line telephone system, the combination with a line-circuit, of -two polarized bellsfconnected therewith for selective signaling, said bells being biased in opposition to each other by the weight of their moving elements, one of said bells being organized to operate with a heavy positive 4alternation of current which will actuate its armature in opposition to the gravitational trend, and a light negativealternation of current which will assistthe gravitational trend in the operation oi' itslarmature in the direction of its normal position, the other bell being' organized to o perate with a heavy negative alternation v of current which will actuate its armature in op'- position to the gravitational trend, and a light positive alternation of current which will assist the gravitational trend in the operation of its armature in the direction of its normal position, and means adapted to be connected with the line-circuit by ,meansof suitable keys for producing the required heavy and light alternations of current, the rneans consistingvoi1 an alternating-current generator and a source of steady current connected in multiple with the alternating-current gener,- ator, substantially as described.

Il. In a party-line telephone system', the combination with two metallic limbs extending from the central station through four substations, of a telephone set at eachoic said substations connected in a normally open bridge eX- tending between the two metallic limbs, whereby the telephone set at any one oi the substations may be individually connected between the metallic limbs, a polarized call-bell at each of said substations, two of said call-bells being' oppositely biased and connected between one of said limbs and theground in their operative condition,-the remaining two call-bells being oppositely biased and connected between the other ,limb and ground in their operative condition, the call-bells being organized to require a major. alternation to actuate the biased moving element in opposition to the biasing -force thereof, and a minor alternation to assist the biasing force in the retracting strokeof said biased moving element, four keys at the central station organized to connect sultable alternating current ,over the metallic limbs it'or selectively operating the four bells, two of said keys being connected with posi-l tive steady current and an alternating-current generator in multiple for producingv the required major and minor alternations for operating the two simil-ar biased bells on either metallic limb, and means in series with the positive steady-current source tov prevent short-circuit of the alternating-.current generator,the,remaining two keys being conneeted vwith negative steady current andsaid 'alternating generator in multiple for producing the required major and minor alternations for operating the remaining two similar biased bells on either metallic limb, and means in series with the negative steady-current source to `prevent short-circuit of the alter. nating-current generator, substantially as described. v l

l2. In a lparty-line telephone system, the combination'with a line-circuit, of two oppositely-biased call-bells connected therewith in their operative condition, one4 of said bells being organized to respond to a major positive alternation and a minor negative alternation, and the other bell. being organized to respond to a major negative alternationand a minor positive alternation, and means organized to selectively ring either one of the IOO bells to the exclusion of the other, the means consisting of an alternating-current generator, and a source of steady currentconnected inv multiple with said alternating generator for suitably'counteracting one alternation or half-wave in the act of selectively ringing one bell, and a keycto substitute alsteady-current source of opposite polarity inthe act of se-` lectively ringing the oppositely-biased bell, and a resistance-coil inrseries with the steadycurrent source to prevent short-circuit of the alternating generator, substantially as described.

ISO

13. In a party-line telephone system, the combination with a line-circuit, ot' two oppositely-bi'ased call-bells connected therewith in their Operative. condition, one ot' said bells being organized to respond to a major positive alternation and a minor negative alternation, and the other bell being organized to respond to a major negative alternation and a minor positive alternation, two keys for selectively ringing the bells, an alternating-current generator, a source otl positive steady current, and a source of negative steady eurrent, one of said keys being organized to connect the alternating' generator and the source ot' positive steady current in multiple tor producing the major positive and minor negative alternations, and the other key being organized to connect the alternating generator and the source ot negative steady current in multiple for producing the major negative and minor positive alternations, and a resistancecoil in series with the steady-current sources to prevent short-circuit ot' the alternating generator' while ringing' either one ot' the biased call-bells, substantially7 as described.

14. In. a party-line telephone system, the combination with a line-circuit of two polarized call-bells connected therewith for selective signaling, said bells being biased in opposition to each other by the weight or gravitational trend of their moving elements or gong-striking mechanism, one of said bells being organized to operate with a heavy positive alternationwhich will actuate its g'ongstriking mechanism in opposition to the gravitational trend, and a light negative alternation which will assist the gravitational trend in operating the gong-striking mechanism toward its normal position, the other bell being organized to operate with a heavy negative alternation which will actuate its gong-striking mechanism in opposition to the gravitational trend, and a light positive alternation which will assist the gravitational trend in operating the gong-striking mechanism toward its normal position, two keys for selectively ringing' the bells, an alternating-current generator, a source of positive steady current, and a source of negative steady current, one ot' said keys being' organized to connect the alternating generator and the source of positive steady current in multiple for proy ducing the heavy positive and light negative alternations, and the other key being organized to connect the alternating generator and the source of negative steady current in multiple for producing the heavy negative and the light positive alternations, and a resistance-coil in series with the steady-current sources to prevent short-circuit ot' the alternating generator while ringing either oneot' the biased call-bells,substantially as described.

l5. In a party-line telephone system, the combination with a line-circuit, ot' two callbells connected therewith for selective signaling, said bells heilig' (nipositely biased bythe weight oi their lnoving elements, one ol' said bells being organized to operate with a heavy positive alternation which will actuate its armature in opposition to the gravitational trend, and a light negative alternation which will assist the gravitational trend in the operation o'tf its armature in the direction ol its normal position, the other bell heilig' organized to operate with a heavy negative alternation which will actuate its armature in opposition t the gravitatiomd trend, and a light positive alternation which will assist the gravitational trend in the operation of itsarmature in the direction ot' its normal position, means to produce selective signaliiig-current with heavy and lightalternations to ring said bells, the means consisting of a source ol positive steady current, and a source o'le negative steady current, and mechanism to engage either source o't steady current with the linecircuit while ringing one bell totheexclnsion ot the other, and an altermiting-current generator bridged with the engaged source ol steady current while ringing, and a resist ancecoil in the engaged steady-current path, substantially as described.

16. V[n a party-line telephone systen'i, the combination with a line-circuit, oit two polarized call-bells connected therewith tor selective signaling', said bells being oppositely biased by the weight olI their moving elements, and adapted to be rung by means o t an alternating current with one alternation or haltwave ot greater potential than thealternation or halt-wave of opposite sign, an alternatingcurrent generator, a positive steady-current generator, and a negative sternly-current generator, and means to connect tl alternatingcm'rent generator and either ot the steadycurrent generators in multiple and with the. line-circuit for selectively ringing either ot the call-bells tothe exclusion ol the other, substantially as described. l

1.7, len a party-line telephone system, the combination with a line-circuit, ol two polarized call-bells connected therewith Vlor selective signaling' and arranged to be biased in opposition to each other b v the weight ol their moving' elements, an alternating-current generator adapted to be camuccted with the linecircuit in the act oi selectively ringing the bells, and a source of positive steady current adapted to be connected in multiple with the. alternating-current generator tor producing` suitable selective alternatingcurrent lor ringing the positively-biased bell, and a source ol negative steady current adapted to be connected in multiple with the allernating-current generator for producing suitable selective alternating current ior ringing the negatively-biased bell, substantially as described.

18. In a party-line telephone system, the` combination with aline, of two call-bells associated therewith and biased in opposition to lOO llO

each other by the weight of their gong-strikcurrent bridged with said generator for converting thealternating current generated by sald generator into selective sign aling-current,

and a resistance-coil in series with thesteadycurrent source, substantially as described.

' 19. In a party-line telephone system, thel combination with a line-circuit, of two polarized call-bells biased by the weight of their gong-striking mechanism, one of said bells being adjusted to respond to major positive alternations and minor negative alternations, and the oppositely-biased bell being adjusted to respond to major negative alternations andminor positive alternations, an alternatingcurrent generator associated with the line in the act of selectively ringing either call-bell vto the yexclusion oi' the other, and a source of steady current bridged with said generator 4for converting the alternating current generated by said generator into suitable major and minoralternations, and a resistance-coil 1n series with the steady-current source, substantially as described.

Q0. Inaselective ringing telephone system, .the combination with a metallic line-circuit,

or' four polarized call-bells biased by the weight of their gong-striking mechanism, two of said bells being oppositely biased and associated with one limb of the line, the remaining two bells being oppositely biased and associated with the other limb of the line,an alternating-current generator and lmeans to connect the same with either limb of the line, a source of steady current bridged with said rent generated by'said generator into selective signaling-current, and a resistance-coil in series with the steady-current source, substantially as described.

21. `In a party-line telephone system,y the combination with a line-circuit, of two oppositely-biased call-bells connected therewith in their operative condition, an alternating-current generator, and a source or' steady current connected in multiple therewith for producing alternating selective signaling-current with one alternation of greater potential than the alternation of opposite sign, and means to connect said generator andsource of steady current with the line-circuit, substantially as described. v l

22. In a party-line telephone system, the combination with a line-circuit, of two oppositely-biased call-bells connected therewith in their operative-condition, selective signaling apparatus for producing selective signaling- .current with the positive alternations of greater strength .than the negative alternations' for ringing one of the bells, and selective current with the negative alternations oi' greater strengththan the positive alternations Vfor ringing the oppositely-biased bell, the selective signaling apparatus comprising an alternating-current generator and a steady-cur.-

rent generator connected in multiple with each other, and means associated with the line-circuit i'or uniting the selective signaling apparatus with the line-circuit when ringing either call-bellto vthe exclusionof theotlier, subi stantially as described.

23. In a party-line system, the combination of two oppositely-biased call-bells connectedA with a line-circuit, an alternating-current generator connected with the line-circuit, and a source of steady current connected in -multiple with said generator for converting the alternating current generated by said geri- `erator into selective signaling-currents,sub-

tive relation with one limb of the, metallic circuit, the remaining two bells being oppositely biased and in operative relation with the other limb of the metallic circuit, an alternating-current generator, and a source of steady current bridged .with said generator for converting the current generated by said IOO generator into selective signaling alternating currents, and an impedance in series withthe steady-current source, and means to connect the selective signaling-current .with either limb or' the metallic circuit for selectively IIO ringing one of the biased call-bells, substantially as described.

26. In a party-line telephone system, the combination with a line-circuit, .of two oppovsitely-biased call-bells connectedin operative relation therewith, one of said `bells being organized to respond to a major positivealternationA anda minor negative alternation, and

the other bell being organized. to-respond to a major negative alternation anda minor positive alternation, an alternating-current generator, and a source ofsteady current bridged with said generator for converting the current generated by said generator into major and minor alternations, and animpedance in series with the steady-current source,y and means toconnect the generator and steady-current source with the line-circuit in the act of selectively ringingv either call-bell, substantially as described.

rezo

vsteady current and the alternating-current generator in multiple and with the line-circuit in the act of selectively ringing one bell to the exclusion of. the other, substantially as described.

28. VIn a party-line telephone system, the combination with a line-circuit, of two oppositely-biased call-bells connected in operative relation therewith, one of said bells being organized to respond to a major positive alternation and a minor negative alternation, and the other bell being organized to respond to a major negative alternation and aminor positive alternation, a source of positive steady current, and a source of negative steady current, and means to connect either source with the line-circuit in the act et' selectively ringing one of the biased call-bells, and an alternating-current generator bridged with the steadycurrent source for producing the required major and minor alternations when ringing, and an impedance in series with the steadycurrent source, substantially as described.

29. Inaselective ringingtelephone system, the combination with a metallic line-circuit, of four biasedcall-bells, two of said bells being oppositely biased and in operative relation with one limb of the metallic circuit, the remaining two bells being' oppositely biased and in operative relation with the other limb of the metallic circuit, a source of positive steady current, and asource of negative steady current, and means to connect either source with the limbs of the metallic circuit in the act of selectively ringing one of the biased call-bells, and an alternating-current generator bridged with the steady-current source when ringing, and an impedance in series with the steady-current source, substantially as described.

30. In a party-line telephone system, the combination with a metallic line-circuit, of four call-bells, two of said bells being oppositely biased and in operative relation with one limb of the metallic circuit, the remaining two bells being oppositely biased and in operative relation with the other limb of the metallic circuit, all of said bells being organized to ring with major and minor alternations, a source of positive steady current,and a source of negative steady current, and means to conneet either source with the limbs of the metallic circuit in the act of selectively ringing one of the bells, and an alternating-current generator bridged with the steady-current source for producing the major and minor alternations when ringing, and an impedance in series with the sternly-current source, substantiall y as described.

31. ln a party-line telephone xsystem, the combination with a metallic line-circuit, oil two oppositely-biased call -bells associated with each limb of the line, two ol said bells being organized to respond to major positive alternations and minor negative alternations, and the other two bellsbeingl organized to respond to major negative alternations` and minor positive alternations, a source ol positive steady current, and a source oi. negati ve steady current, and means to connect either source with either limb of the line in the act ol selectively ringing one bell, and a source of alternating current bridged with the steady-current source for producing themajor and minor alternations when ringing, and an impedance in series with the stead y-current source, substantially as described.

32. In a selective party-line system, the conlbination with a line-circuit of two oppositelybiased call-bells connected therewith for signaling, the call-bells being organized to require a major alternation to actuate the biased moving element in opposition to the biasing torce exerted thereon and a minoralternation to assist the biasing force in the reti-acting stroke of said biased moving element, means to produce selective signaling-current with major and minor alternations, the means consisting of a source of steady current and a source of alternatingcurrent bridged together when signaling, and a resistance-coil in series with the stez'Ldy-current source, substantially as described.

33. Inaselectiveparty-linesystem,thecoinbination with a line-circuit, of two oppositelybiased call-bells connected therewith for signaling, means to produce selective signaliligcurrent with major positive alternations and minor negative alternations to ring one bell, and major negative alternations and minor positive alternations to ring the other bell, the means consisting of a positive steady-eurrent generator and a negative steady-current generator, and mechanism to engage either steady-current generator with the line-circuit when ringing, and an alternating -current generator bridged with the enga-ged steadycurrent generator when ringing, and a resistance-coil in the engaged steady-current generator path, substantially as described.

34. In a party-line telephone system, the combination with a metallic circuit, of two oppositely-biased call-bells connected with each limb or' the line for selective signaling, one bell of each limb of the line being organized to require a major positive alternation to actuate the biased moving element in opposition to the biasing force exerted thereon and a minor negative alternation to assist the biasing force in the retracting stroke of said biased movingl element, and the oppositely-biased IOO IIO

call-bell on each limb of the line being organized to require a major negative alternation to actuate the biased moving element in opposition to the biasing force exerted thereon and a minor positive alternation to assist the biasing force in the retracting strokev of said biased moving element, means to produce selective signalingcurrent with major positive alternations and minor negative alternations to ring two or' said bells, and major negative alternations and minor positive alternations to ring the remaining' two bells, the means l consisting of a source of positive steady cura source of negative steady current, and mechanism to engage either source with the line, and an alternating-current generator bridged with the engaged source of steady current when signaling, and a resistance-coil in series with'the engaged steady-current source, sub-A stantially as described. I

.36. In a party-linetelephone system, the combination with a line-circuit, of two oppositely-biased call-bells connected therewith for selective signaling,'selective signaling apparatus for producing positive alternations of greater strength than the negative alternations toring one bell, and negative alternations of greater strength than the positive alternations to ring the oppositely-biased call- AIIGSSGS.

bell,the selective signaling apparatus comprisingran alternating-current generator, a positive steady-current generator, and a negative steady-current generator, means associated with the line-circuit and generators to engage either steady-current generator singly and the alternating-current generator in multiple for producing selective current for operating either call-bell to the exclusion of the other, and a resistance-coil inV the engaged steady-current-generator path to prevent short-circuit of the alternating generator while ringing, substantially as described'.

37. In a .party-line telephone system, the combination with two metallic llimbs extending from the'eentral station through four substations, of a telephone set at each of said substations connected in a normally open bridge whereby the telephone set at any one of the substations may be individually connected between the 'metallic limbs, a biased call-bell at each of said substations connected between one limb and the ground, all ofl said bells being organized to ring with major and minor alternations, an alternating-current generator, a.

" THOMAS e. BRAKE.

Witnesses:

A. DURBIN, E. J. AvRIoK.

extending between the two metallic limbs 

